Integrating 3-D Facies Analysis of Glacial Aquifer Systems with Groundwater Flow Models: Examples from New England and the Great Lakes Region, USA

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1 Integrating 3-D Facies Analysis of Glacial Aquifer Systems with Groundwater Flow Models: Examples from New England and the Great Lakes Region, USA Stone, B.D., J.R. Stone, J.P. Masterson, and D.W. O'Leary U.S. Geological Survey; Byron Stone at Modern ground-water flow models, geotechnical studies, and science-based land-use planning require knowledge of the distribution of surficial earth materials from land surface to the top of bedrock (e.g., Masterson and others, 1997a,). To be useful, modern geologic maps must portray such information three dimensionally in a way that is consistent with the regional stratigraphic framework, geotechnical classifications, and the most recent understanding of geologic depositional processes (Masterson and others, 1997b, Central Great Lakes Geologic Mapping Coalition, 1999). The evolution of 3-D geologic maps of glacial meltwater deposits demonstrates new 3-D mapping and analytic techniques now available for these studies in the desktop computer environment. The highly productive glacial aquifers in the valleys and lowlands of the northern U.S. are composed of ice-channel, glaciofluvial, glaciolacustrine, and glaciomarine deposits, which traditionally have been differentiated as lithostratigraphic formations (e.g., Willman and Frye, 1970; Lineback and others, 1983; Stone and others, 2002). Within these formation-rank units, informal allostratigraphic units comprising numerous glacial lakes and outwash systems can be distinguished (Stone and others, 2002; U.S. Geological Survey, 2001; Stone and others, in press). These individual lake and stream deposits are further related to ice-margin retreat positions in the relative stratigraphy of ice-sheet recession in various depositional basins. Detailed geologic maps (1:24,000 scale) permit precise mapping of meltwater sedimentary units within each glacial lake or valley outwash system (Jahns, 1941 and 1953; Koteff, 1966). These units, known as morphosequences (Koteff and Pessl, 1981), are the smallest mappable stratigraphic units on detailed geologic maps. Morphosequences are bodies of stratified meltwater sediments that are contained in a continuum of landforms, grading from ice-contact forms (eskers, kames) to non-ice-contact forms (flat valley terrace, delta plains), that were deposited simultaneously at and beyond the margin of a glacier, and graded to a specific base level. Morphosequences each consist of a proximal part (head) deposited within or near the ice margin, and a distal part deposited farther away from the ice margin. Both grain size and ice-melt collapse deformation of beds decreases from the proximal to the distal part of each morphosequence. The head of each morphosequence is either ice marginal (ice contact) or near ice marginal. Ice-marginal morphosequences were deposited in contact with the ice margin. The heads of many ice-marginal morphosequences extended well up into the ice margin in channels and tunnels; melting of adjacent and subjacent ice caused the collapse of these headward sediments to lower positions where they commonly were buried by later sediments. Near-ice-marginal morphosequences were deposited short distances in front of the ice margin, separated from it by valley segments too steep for deposition. The surface altitude of fluvial sediments in each morphosequence was controlled by a specific base level, either a glacial-lake water plane or a valley knickpoint. Few morphosequences extend distally more than 10 km, and most are less than 2 km in length. In any one basin, individual morphosequences were deposited sequentially as the ice margin retreated systematically northward. Consequently, in many places the distal, finer grained facies of a younger morphosequence stratigraphically overlies the proximal, coarse-grained facies of a preceding morphosequence. Six original types of morphosequences diagrammed by Koteff and Pessl (1981) are recognized across the northern U.S. Lacustrine-fan and marine-fan types are known from the northeastern U.S. (Stone and others, in press). Examples of three new types of morphosequences, deposited within holes 1

2 and channels in glacial ice, are now known. Figure 1 presents these ten types of morphosequences relative to proximal-to-distal and fluvial-to-lake/marine depositional environments of the original classification. The names of these deposits have been modified (Stone and Stone, in press) from the Figure 1. Relationships of ten types of meltwater morphosequences to proximal-to-distal glacial meltwater environments, and high-energy fluvial to low-energy glacial lake/marine environments. Trends in the varying proportion of gravel, sand, silt, and clay in these deposits are shown schematically. original terminology of Koteff and Pessl (1981) to emphasize the descriptive features and the depositional environment of each morphosequence type. Within the continuum of landforms, each morphosequence contains an assemblage of coarse- to fine grained sedimentary facies that were deposited contemporaneously. A meltwater sedimentary facies is a body of sediment that contains strata of similar texture and structure, and which is differentiable from other bodies of sediment possessing different lithic characteristics. Glacial meltwater sedimentary facies are combined either in facies assemblages within morphosequences, or are present as single mappable bodies of sediment in the distal parts of basins (Figure 2). Morphosequences typically consist of combinations of downstream-fining glaciofluvial and glaciodeltaic facies, which are related to specific environments of deposition along the path of meltwater flow from ice-proximal to distal environments (Figure 1). Through comparative studies of modern active environments (e.g., Boothroyd and Ashley, 1975; Gustafson and Boothroyd, 1987), these descriptive facies may be related to depositional facies within the stratigraphic framework of Pleistocene deposits (Stone and Force, 1982; Stone and others, 2002; Stone and others, in press). Recent mapping studies demonstrate how deep exposures, boreholes, geophysical surveys, and water-well records are used to subdivide morphosequences into a series of related sedimentary facies (U.S. Geological Survey, 2001). The following section on Sedimentary Facies in Glacial Meltwater Deposits explains and illustrates (with diagrams) the 11 sedimentary facies (shown on Figure 2) that are recognized within the meltwater deposits of the region (modified from Stone and others, in press). Facies characteristics are distinct enough that these material units may be used as hydrostratigraphic facies in regional and local ground- 2

3 water flow models (e.g., Anderson, 1989). Representative hydraulic conductivities, based on pump tests, infiltration tests, and contaminant plume flow velocities from locales with well documented 3-D stratigraphic control, are presented and highlighted (italicized) in this section. Figure 2. Assemblages of meltwater sedimentary facies within selected types of morphosequences (modified from Stone and others, in press). See section below on Sedimentary Facies in Glacial Meltwater Deposits for a detailed description of the 11 sedimentary facies. 3

4 SEDIMENTARY FACIES IN GLACIAL MELTWATER DEPOSITS GLACIOFLUVIAL SEDIMENTARY FACIES Sand and Gravel Ice-Channel Glaciofluvial Facies Pebble-cobble gravel beds, massive planar bedded, planar-tabular crossbedded Interbedded medium-coarse sand, planar bedded, planar-tabular and trough crossbedded, ripple laminated Minor sets of silt and clay laminae Three to 30 m total thickness Horizontal hydraulic conductivity 88 m/day, In ice-contact esker and ice-channel deposits Coarse Gravel Glaciofluvial Facies Cobble-boulder gravel beds, coarse sand matrix, massive planar bedded, planar-tabular crossbedded Minor interbedded medium-coarse sand beds, planartabular and trough crossbedded, No silt or clay beds Two to 15 m total thickness Horizontal hydraulic conductivity 106 m/day, At ice-marginal head of morphosequences Sand and Gravel Glaciofluvial Facies Pebble-cobble gravel beds, massive planar bedded, planar-tabular and trough crossbedded Interbedded medium-coarse sand beds, planartabular and trough crossbedded, Minor sets of silt laminae, minor clay One to 15 m total thickness Horizontal hydraulic conductivity 88 m/day, In outwash deposits and as delta topset beds Coarse Pebbly Sand Glaciofluvial Facies Coarse pebbly sand beds, massive planar bedded, planar-tabular and trough crossbedded Interbedded pebble gravel beds, and mediumcoarse sand beds, planar bedded and ripple laminated Minor sets of silt laminae, minor clay One-half to 8 m total thickness Horizontal hydraulic conductivity 73 m/day, In distal outwash or delta topset deposits 4

5 \GLACIODELTAIC SEDIMENTARY FACIES Sand and Gravel Glaciodeltaic Foreset Facies Pebble-cobble gravel in planar-tabular and trough foreset beds, parallel bedded, minor openwork gravel Interbedded fine-coarse sand in trough foreset beds, parallel bedded, planar-tabular crossbedded, and Some sets of silt laminae, minor clay, minor flowtills Two to 30 m total thickness Horizontal hydraulic conductivity 85 m/day, In proximal parts of deltaic deposits Fine-coarse sand in planar-tabular and trough foreset beds, parallel bedded, Interbedded fine pebble gravel in planar-tabular foreset beds, parallel bedded Interbedded sets of draped silt and minor clay laminae Two to 30 m total thickness Horizontal hydraulic conductivity m/day, Ratio of horizontal to vertical conductivity 5-10:1 In central and distal parts of deltaic deposits Sandy Glaciodeltaic Foreset Facies Fine-medium sand in planar and trough bottomset beds, parallel bedded, Interbedded sets of draped silt and minor clay laminae Two to 10 m total thickness Horizontal hydraulic conductivity m/day, Ratio of horizontal to vertical conductivity 10-30:1 In distal parts of deltaic deposits Fine Sand Glaciodeltaic Bottomset Facies GLACIAL LAKE/MARINE-BOTTOM SEDIMENTARY FACIES Sand and Gravel Glaciolacustrine Fan Facies Pebble-cobble gravel, coarse sand, and minor flowtill in planar-tabular and trough foreset beds, parallel bedded, planar-tabular crossbedded Local compact till at top of section Minor interbedded fine-medium sand, parallel bedded, Minor interbedded sets of draped silt and minor clay laminae Two to 20 m total thickness Horizontal hydraulic conductivity 85 m/day, In proximal parts of lacustrine/marine fan deposits 5

6 Fine-medium sand in planar and trough bottomset beds, parallel bedded, Interbedded sets of draped silt and minor clay laminae Two to 20 m total thickness Horizontal hydraulic conductivity 45 m/day, Ratio of horizontal to vertical conductivity 10:1 In distal parts of lacustrine/marine fan deposits Sand-Silt Glaciolacustrine Fan Facies Fine sand-silt, irregularly spaced parallel laminae, Interbedded sets of silt and clay laminae Marine facies contains massive silt-clay 10 to 60 m total thickness Horizontal hydraulic conductivity 9 m/day, Ratio of horizontal to vertical conductivity 100:1 In lake-bottom deposits proximal to deltaic deposits Sandy Glacial Lake or Marine Bottom Facies Silt-fine sand and clay in irregularly spaced parallel laminae or regularly spaced varve couplets, minor Minor interbedded fine sand, parallel laminated, 2 to 60 m total thickness Horizontal hydraulic conductivity 3 m/day, Ratio of horizontal to vertical conductivity 100:1 In distal lake-bottom deposits Silt-Clay Glacial Lake-Bottom Facies References Anderson, M.P Hydrogeologic facies models to delineate large-scale spatial trends in glacial and glaciofluvial sediments: Geological Society of America Bulletin 101, p Boothroyd, J.C. and G.M. Ashley Processes, bar morphology, and sedimentary structures on braided outwash fans, northeastern Gulf of Alaska: in Jopling, A.V. and B.C. McDonald, eds., Glaciofluvial and Glaciolacustrine Sedimentation: SEPM Special Publication 23, p Central Great Lakes Geologic Mapping Coalition Sustainable Growth in America's Heartland: 3-D Geologic Maps as the Foundation: U.S. Geological Survey Circular, 17 p. 6

7 Gustafson, T.C. and J.C. Boothroyd A depositional model for outwash, sediment sources, and hydrologic characteristics, Malaspina Glacier, Alaska: A modern analog of the southeastern margin of the Laurentide Ice Sheet: Geological Society of America Bulletin, v. 99, p Jahns, R.H., 1941, Outwash chronology in northeastern Massachusetts [abs.]: Geological Society of America Bulletin, v. 52, no. 12, pt. 2, p , Surficial geology of the Ayer quadrangle, Massachusetts: U.S. Geological Survey Geologic Quadrangle Map GQ 21, scale 1:31,680, explanatory text. Koteff, C Surficial geologic map of the Clinton Quadrangle, Massachusetts: U.S. Geological Survey Geologic Quadrangle Map GQ 567, scale 1:24,000, explanatory text. Koteff, C The morphologic sequence concept and deglaciation of southern New England, in Coates, D.R., ed.: Glacial geomorphology: Binghamton, N.Y., State University of New York, Publications in Geomorphology, p Koteff, C. and F. Pessl Jr Systematic ice retreat in New England: U.S. Geological Survey Professional Paper 1179, 20 p. Lineback, J.A., N.K. Bleuer, D.M. Mickelson, W.R. Farrand, R.P. Goldthwait, G.M. Richmond (editor), and D.S. Fullerton (editor) Quaternary geologic map of the Chicago 4 by 6 Quadrangle, United States: U. S. Geological Survey Miscellaneous Investigations Series Map, No. I 1420 (NK-16), Scale 1:1,000,000. Masterson, J.P., D.A. Walter, and J. Savoie. 1997a., Use of particle tracking to improve numerical model calibration and to analyze ground-water flow and contaminant migration, Massachusetts Military Reservation, western Cape Cod, Massachusetts: U.S. Geological Survey Water-Supply Paper, No. W 2482, 50p. Masterson, J.D., B.D. Stone, D.R. Walter, and J. Savoie. 1997b. Water resources of western Cape Cod: U.S. Geological Survey Hydrologic Atlas HA-741, map scale 1:48,000, explanatory text. Stone, B.D., and E.R. Force Sedimentary sequences and petrology of glaciolacustrine deltas, eastern Connecticut, U.S.A.: International Association on Sedimentology Congress, Aug , 1982, Hamilton, Ontario, Canada. Stone, B.D., S.D. Stanford, and R.W. Witte Surficial geologic map of northern New Jersey: U.S. Geological Survey Miscellaneous Investigations Map I-2540-C, scale 1:100,000; 3 sheets, and a 41-page explanatory pamphlet. Stone, J.R., J.P. Schafer, E.H. London, M. DiGiacomo-Cohen, R.S. Lewis, and W.B. Thompson. in press. Quaternary geologic map of Connecticut and Long Island Sound Basin, with a section on sedimentary facies and morphosequences of glacial meltwater deposits by B.D. Stone and J.R. Stone: U.S. Geological Survey Scientific Investigations Map 2784, scale 1:125,000, 2 plates and a 41-p pamphlet. U.S. Geological Survey Surficial geologic map of Berrien County, Michigan; Edited and integrated by B.D. Stone: U.S. Geological Survey Digital Open-file Report , scale 1:100,000, explanatory text. Willman, H.B., and J.C. Frye Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p. 7

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